1. Field of the Invention
This invention relates to etching semiconductor wafers on one side and more particularly, refers to a new and improved method of etching semiconductor wafers on one side without covering the other side with a varnish or similar coating.
2. Description of the Prior Art
When processing semiconductor materials into certain components there is often the need to etch one circular surface of a semiconductor wafer only while the etchant must be kept away from the opposite surface of the semiconductor wafer.
According to the commonly applied etching methods, the semiconductor surface not to be etched must be covered with a varnish for this purpose. This varnish must be dried by heating, whereupon the second, uncoated semiconductor wafer can be etched. This requires expensive operations such as rinsing and drying of the wafers, and finally the varnish on the reverse side must be removed, again requiring rinsing and drying operations after removal of the varnish. Since all these operations are usually performed by arranging several semiconductor wafers in a group, each individual operation requires a regrouping. To etch semiconductor wafers on one side requires approximately twenty process steps to be carried out, consuming much labor at considerable cost. Moreover, the need of deionized water to rinse the semiconductor wafers and the consumption of chemicals and energy are quite substantial.
In addition, damage in the form of contamination is often caused on the varnished semiconductor surface, because sometimes varnish residues are not removed completely, or else scratches or fractures are caused on the treated semiconductor wafer in consequence of the many individual operations to which the semiconductor wafer is subjected.